Assessment of Grashoff cooling potential in micro heat pipes: an experimental study

Some silver tapered and copper flat MHPs (micro heat pipes) have been investigated. To control the temperature of a simulated grid, the MHP´s condenser was kept open to ambient air as may be done in most terrestrial applications, and tested under varying Grashoff numbers. As a result of free convection heat flux transfer from their condensers, the MHPs were found to be nearly insensitive to gravitational force due to their low Bond number. In the top heating mode, up to a certain degree of tilt, an unusual increase in heat flux transfer has been observed in all four types of MHPs. The employment of aluminum ribs on the condenser in silver tapered MHPs is found to be advantageous. The devices can be used effectively in microelectronic component cooling, isothermalization of leading edges of wings of spacecraft, and in surgical cryogenic probes